Colored granulated material



O6. COMPO smous, coume e PLASHQ 4 Patented ilune 26, 1945 I CrossReference UNITED STATES T as? COLORED GRANULATED MATERIAL Clifford L.Jewett, Minneapolis, Minn, assignor to Minnesota Mining & ManufacturingCompany, St. Paul, Minn, a corporation of Delaware I No Drawing.Application April 8, 1939, Serial No.

266,861. In Canada January 30, 1936 20 Claims.

This application is a continuation-in-part of my co-pending applicationSerial No. 700,632, filed December 1, 1933. It is alscacontinuationin-part of my application Serial No. 749,481, filed October22, 1934 and of my application Serial No. 233,293, filed October 4,1938. a

This invention relates in general to comminuted or granular material, ofa mineral, siliceous or like nature, and to coating compositions orcolored coatings which are substantially insoluble and/orweather-resistant. It more particularly relates to an improved processfor treating such granular material and to the resultant product. Myinvention especially concerns the production of such a granulated ormineral material, or the like, having a water-resistant, color-bearingcoating suitable for embodiment in roofing material or the like, forexample, and while the invention is described and illustrated inconnection with colored granules, and processes for making the same, tobe incorporated in roofing materials such .as shingles and the like, toweatherproof and/or beautify the same, it will be understood that thisinvention finds awide field of utility which is not restricted by theexamples or illustrations employed.

This application is based upon or is a continuation-in-part of mycopending application Serial No. 700,632, filed December 1, 1933.

The product of this invention may be incorporated as a coating for aroofing shingle or as an aggregate for incorporation in artificial stonesuch as cast stone and the like, and for the base granule I may employsubstances of amineral, siliceous or like nature, whether of natural orartificial origin, such, for example, as uartz,

and other baked clay and similar material, 22rcelain, terra cotfi orother ceramic wastes or cement compositions.

' In the prior art relating to this subject, particularly where aceramic coating is applied to the mineral base granule under theapplication of high temperatures to produce a glaze thereon, it isnecessary to employ care in selecting a base granule which must berefractory and free from impurities which tend to discolor the glaze.

. I am enabled to employ a relatively inexpensive base granule, and theordinary impurities found in mineral materials, such as iron andmanganese, have no effect on the resulting color obtained in thecoating, and thus practically any gravel pit may yield a granulesuitable for coating according to the process of my invention.

The coated granule, according to this invention, may, for example, beincorporated as ,a weather-resisting or beautifying coating in a sheetcoated with abituminous, asphaltic or other adhesive or binder, e. g.for forming roofing material either in the form of rolls or shingles, or

the base granule coated according to this invention may be incorporatedin cast stone, concrete, plaster and the like.

Heretofore, efiorts have been made to treat crushed mineral materialwith a color bound to the granule with an organic bond, but this isunsuited for ma'ny purposes, inasmuch as the colors are onlyindifferently permanent, and the organic bond does not have the life orageing characteristics necessary, particularly where it is desired toemploy the granules in exposure to the atmosphere, as in roofingmaterial or in cast stone and the like.

As an alternative, inorganic bonds have been experimented with, andchief among those known 5 to me are the type employing sodium silicateas a dried film on, for example, acalcium-containing base attemperatures of the order of 450 F, or

those in which certain combinations of sodium silicat and glaze-forminmetal com unds have Been employed at relatively High temperatures toproduce a fused coating or glaze on the surfaces of the granules orcomminuted particles. So far as I know, no one prior to this inventionever recognized the merit and advantages of coatings, 5 especiallycolored coatings, comprising the reaction product of a cla suchas kaolinwith sodium silicate, which coa mg or product, according to" tliisin'vention is desirably produced at temperatures substantially above thepoint of dehydration 40 of the alkali silicate bi t b,elow the fusionpoint oumsiiicatelmixlwfiich is also normally below the fusion point ofthe sodium silicate), temperatures ranging from 850 or 950 F. up toabout 1450 F. being illustrative reaction temperatures. Where an alkalimetal fluoride, such as cryolite hereinafter mentioned, is present inthe c ay-s ium'silicate mix, a'maximum temperature of the order of 1050F. is usually sufficient; while in the absence of an alkali metalfluoride (as for example where kaolin and sodium silicate aresubstantially the only reactants),a top temperature of the order of1350, 1400 or even 1450 F. is often desirable, so long as the granulesare kept below the fusion point of the sodium silicate and/or of theykaolin-sodium sili- Examiner J5? 2,379,358

cate mix, in order to produce granules having a coating which ispreferably unfused and which Among the defects of those older methodsand the resulting products or articles which limit their possible useare the lack of strength of color or proper tone of color, or tendencyto blooming, lack of permanence of color and the limit of the range ofcolors available.

In the prior art known to-me employing silicates, the temperaturesdisclosed in such-prior, art are insuflicient to produce an insolublecoat ing composition on the granules, and, further more, therelationship between the silicates and other ingredients disclosed inthe ,prior art are insufiicient or unsatisfactory to ;provide acementwhich is insoluble and weather-resisting. v The P incipal objects andadvantages of this inventionzresidein the-provision of an improvedarticle of manufacture,-coated colored granules, which may bemanufactured with a wide range of colors of extremepermanence and at areasonable :cost; theprov-isionof treated granules ofthe characterreferred to in which a good bonding action can be attained betweenthebase granule andthe' color-bearingcoatinz; the provision ofunimproved granulated material suitable for use when exposed to theweather, in which desired color effects may be attained and in whichsteps of carrying-out-the process of manufacturing the same .arereducedso as to reduce the cost of manufacture, v

This invention also contemplates an improved method of applyingacolor-bearing coatin to mineral, siliceous or like granulesorparticles,which does not necessarily require, and-intact, preferably avoids {theemployment oithe extremely highi mp ratures usually foundnecessexy inproducing; glassycoatings; ,the provision of an improved process inwhich the reaction products of a water-soluble silicate and a materialcontaining -,a me 10 x1 e, or a mixture of metal oxides or compounds ofaluminum or equiva en especia y acay, are employ .for incorpoartion in acoating e-appl-iedto amineral or other; granule, especially --a.substantially inert granule; the provision oian improved process andresulting article in which the silicates, such as sodium silicate in aueo solution,;-and aluminife' rous materials or ,metalllcoxide-contraining components such :as clays, especially those of thenature of kaolin (plus, if desired,

certain amounts otaluminifero'us materials, such as aluminium silicate,sodium alulni un l silicate,

together with 5' pigment tdforin a cement.colorbearingooating'bmindividual granules; ,the provision of an improved v article.ofqmanufacture having is. "color-bearing coating on the individualgranules thereofincluding the heat reacted zproduct-ona-silicate anda-clay; theprovision bran improved granulated material havinga.eolorebearing, coatingwherein .the coating is rendered insoluble by theproductionof. a heat reaction product of sodium silicate and ;clay orof: a mixture comprising pr'consisting substantially of an elk-allsilicateiand .a clay such as kaolin, including a yspigment; :theqarovision .of

an improved process for the production of granulated material having theindividual granules provided with a weather-resisting and insolublecolor-bearing coating wherein an improved step 5 of treating the coatingis employed for dehydrating and insolubilizing the coating for itsentire depth, but, at the same time, preferably avoidingifusion of thecoating mixture and thus avoiding deleterious effects onthe coating. Thepresent invention has, as further objects, 1 the provision of animproved granulated finished :material having .a colored coating whichis permanent in its adherence to the granule; a coatinglmaterial :whichhas 'the property of desired l5 fluidity-by virtue of the processemployed in the course of its application to the granule and which,coating material, itherefore, readily spreads on .;the base granule,assisting in attaining the deslred permanence of adherence to thegranule,

'20 and at the same time possesses suitable coefficientscoi expansionand contraction so thatpthe color coatingmay be suocessfullyfifipliedwn.a wide range of different materials forming the base granule orparticle .to be coated.

For the purposecf-my-jnvention, I haveemployed quartzite granules, dueto ,theirrelatively inert cliaramrlmdtfieir ready availabiiityubut itwill be understood that,by keeping the temperatures withinlimitshereinafter pointed out,

so e. g..by.use,of arotary kiln ,of controlled temperatures, these andother gran les may haemployed for the purpose, such, for,example, :ascommon gravel, slate, gannister, -etc., [as well as crushedpofceIaI'ii"'-.and \the like. The .base

plays as a coating composition an inorganic 'heat reaction pr no 0 a 1ca preferably sodium we, and -a clay, such,;for,example, asm (6 or, ifkaolin no .used, clays'of the natured yrophyllite, kyanite and/orbentonite, and'the We used, and the particular ingredients which-I haveemployed as hereinafter pointed out, when treated according to myprocess, produce a reaction product or. coating composition which issubstantially insoluble in waterwand is Weather -resistant even under,various changes in weather conditions, it gbeing'rene of-the aims ofthis inventionto produoeacoating containing 66 themeactiomproduct 0L6:stlicate and a clay, especially a hydroplastic cla -e. H-'kB.O1ln,Whe11e in a substan' ha I aefiydrationof mixture takes place without,however, fusion thereof, :so; that .a coating havingimproved.utilityrandmppearno time will be attained. and aewideohoiceisrziven in the selection ,of the base granulezlan d coloring materialor pigments. 'However, :it -.\will .be .understood that coatingcompositions :comprising the reaction product of hydrous'iplastic:clay.;and 05 alkali silicate are :broadly comprehended although thereaction prodnctmay :be. itra sintered state, oreven inia.fusedzstatezalthough the completely fused materiaL-lsmot. asadesirableasthe unfused coating or the .iclayssodium silicate :solid 70 phasereactionypnoduca i l v Thus the. preferred .coatingof myinvention may beconveniently -.termcd 1a'high' temperature or ;heat cementitiousrcaction:iproduct". nr-cement, and where thisexpression is employedherein. and

76 in the claims; Imcan torincludematerials or com,-

06. cowcsmoua comma OR PLASTIC binations of materials which are heatreacted to an extent above dehydration temperature of the alkalisilicate but below the temperature at which the combination of materialswould completely fuse.-

As herein pointed out, the mineral base granule may be of any materialwhich will withstand temperatures of the degree necessary to produce thereaction between the silicate and clay without disintegration of thegranule, and a suitable pigment to be employed for imparting color tothe V coating should also be capable of withstanding the temperaturenecessary to produce the desired final coating.

The bon in one of its forms in holding the pigment in he coating to thegranule is substantially a high temperature reaction product or cementproduced by the reaction of sodium silicate and a clay such as kaolin,or in other its forms may employ with the clay substitute materials suchassodium silicate with feldspar and/or c oli sodium silicate may bepartially replaced with certain alkali compounds of aluminum and usedwith clay', with or without feldspar or the like, at temperatures which,for my purposes, I have found to range above 450 C. (850 F.) and usuallyabove 1000 R, which temperatures are far above the dehydration point ofthe sodium silicate. While any suitable means known to those skilled inthis art may be employed for attaining such temperatures and effectingthe desired reaction and/or coating operation, one of such means whichis very satisfactory is a rotary kiln, which may be slowly rotated, e.g. at the rate of 1 to 4 R. P. M. so as to a itate the granules as theyare heated. While the granules may spend varying times in their passagethrough the kiln, illustratively their time of passage may be fromseveral minutes to a. couple of hours. /4 to 1 /2 hours beingillustrative. During their passage through the kiln, the granules may bewithin the temperature range above 850 F. for less than half the time;for example during one operation where the time of passage is a littleless than an hour, the granules were maintained within a temperaturerange above 850 F. for approximately onequarter of the total time ofpassage. In my production of the coating, reaction is produced betweenthe sodium silicate and clay which is substantially a dehydration ofboth, with a subsequent reaction or sint'erinf together of the two toform a hard, strong an non-porous insoluble and weather-resisting cementor coating con- I taming a coloring compound.

I have found in one of the forms of my invention that the ingredients ofthe color-bearing coating may be combined in the following proportions:

Granulated mineral (quartzite etc.) to the extent of 500 rams is mamawith 10 cubic centimeters of a sodium silicatesolution. This sodiumsilicate solution may be of a specific gravity of 1.30, and the sodiumsilicate may have a ratio of soda to silica as indicated by the formulaNam-3.25 $102; I have obtained excellent results with a sodium silicateof this character.

To this mixture of sodium silicate and mineral I then add five grams ofkaolin which is a well insteadof'stidiifiii silicaF'F'e a one', or theThe above formula may be presented in table I form, as follows: 7

. Formula 1 g V I Pounds Granules (quartzite, etc.) 2000 Kaolin 20. Rediron oxide 16-28 Sodi ate solution of 1.3 spec. grav--- 52 Additionalwater if desired to facilitate mixing.

The proportions of sodium silicate to kaolin or equivalent may be eitherincreased or decreased by 25 percent or more and still give a goodcoating, the above example illustrating good proportions.

By preliminarily wetting or moistening the granules with the aqueoussolution of sodium silicate they are made more receptive to the coatingcomposed of the clay and colorpi ment such as red iron oxide,Ultramarine blue or cobalt blue, a green pigment c ompri sing or consismg 0 c o'me oxide, ab ac pigment comprising carbon 'ck, m e. V I

The granules thus coated are then dried and heated to subject them to atemperature of from 850 to 1400 F. (450 to 750 C.) or higher, toptemperatures within the range of 1000 to 1450 F. being'common. Under theapplication of heat in controlled amount, such a reaction between thesodium silicate and clay results as to form an insoluble andweather-resisting coating on the individual granules which permanentlyretains the pigment so that a color-bearing coating is thus produced. Inother words, a substantially non-blooming insoluble coating is producedwhich is substantially free of water-soluble salts of sodium.

I have found that excellent results are obtained at temperatures evenabove 1400" F., but the bearing coating of best quality by theemployment of much higher temperatures for reaction purposes than haveheretofore been employed for getting cementitious combinations. Forexample, it is well known in the prior art to employ temperaturesranging from 900 F., to as high as 1800 F., for the purpose of producinga fused glaze, depending, of course, on the fusing tern vperatures ofthe materials employed. It is not, however, known to me in prior art toproduce a hard weather-resisting heat solidified cement withtemperatures within the range beginning at or above the dehydrationtemperatures of the ingredients of the mixture, but controlled below thefusing temperature of the particular mixture employed, especially wherethe coating ingredients comprise a hydroplastic clay or a kaolinlikematerial and an alkali silicate; nor is it known to me to react hydrousplastic clay and alkali silicate above temperatures of the order of 850or 950 F., whether below the points at which the ingredients or productsthereof will fuse or not, to produce weather-resistant coatings forgranules which are substantially free from watersoluble alkali or sodiumsalts. These are among the novel features of my invention.

It will be understood, therefore, that my invention in its preferredaspect comprises the choice or use of that range of temperatures inwhich important reactions and combinations take place maximumtemperature employed is preferably not, howeven-byvfusion; e.-. g.temperatures within the range of 850 or 900 F. up to::1400."r.-1456?-F., the particular temperature. or range of temperatures depending uponthe fusion point of the I claye'silicate mixture and: upon. otherfactors: such as the presenceor absence. o.other.ingredi+- entssuch as.cryoliteabove mentioned.

Though coating compositiona: 05? the: general; naturezindicated .by the-.abovaiormula .arepre-.-.-

ferred, other formulae which have served to produce highlyefficien-tand'attractive-color bearing coatings, especially wherea clay suchas-kaolin Or pyrophyll-i-te isalso present in' themix, employ. severaldiiferent forms of ingredients; Ineach of these formulae, however, itwill be seen that-:1

employ-aningredient containing ametallic oxide and an alkali silicateor: their equivalent; Such variations: are exemplified below:-

A formula-containing feldspar and sodiumzsiti cateis= as follows:-

y, Y Formula) guartz "gram-sin 500 Eeldspar-(powdered) -do. l0 Redzironoxide: do 75 Sodium silicate solution -cc; 10.

Water: cc 5;

'Likewise a. formula employing cryolite maygbe as'followst- Formula 3.

Quartz; "grams". 5% Gryolite. (sodiumaluminum-z fluoride. (p ovvdered).-"grams" 5;. Redironcxide d0;.. 7 5 Sodiumsilioate solution cc 10. Watercc 5;

Other formulae, though not as desirable as the above illustrated coatingmaterials foruse-in the particular coating operation of" this invention;include:

From the foregoing formulae it will be observed that. the ingredientssuch: aszfeidspar and clay, e. g. kaolin; each contain. proportions ofmetallic oxides in: combinations; while the oryolite is a sodiumalumino;fluoride which comprises. a: metallic fluoride-instead of metallic oxideWherefeldspar or cryolite are mentioned; it: will be understood that:aportiom (ea g. one-quarter, one-- half; on-more). of the weightisozindicated may becomposed: of kaolin: or thelike and also,wheresodiumsaiuminate or sodiumdichromate arementioned, it!williboxunderstood-that sodium silicatemay be employed in lieu: of suchingredients. However; whene sodium'silicate repla-ces sodiumdichromate,. the coloring ingnedient on pigment T0 must be separatelypruvidedifon Itwill also berecognizedi that the sodium; silioate-,.sodium: aiuminate and sodiumdiohromate ingredients-specified: herein(though sodium= silioate: has many'advantages over: the-other twoinen'raesai producing red; blue and other particular coat, ings)mayb'echaracterizedasot a group of alkalh. bearing.- components andserve: to lie/reacted upon;

by .clay.or the metallic. oxide-containing: ingredih' etcrl .-to:provide. afinished coating material of any desired color.

It wilLbeaunderstood; ofscourse; that; while I haver.-specified..a:s0dium silicate-0t acertainisperr cine-gravity and-have alsos ecified.one=examp1 otjtheproportions of sodium silicate-to kaolin .or; likeclay. rand pigment; .this.-;formula. is subiecti tom variation :to suittdigfierent conditions. and the pig!- ment:m o';. e-.changed orsvariedtoattain different. tones of; coloring; desired.

It; is to..- be understoodthat. the-.- temperaturerange is. also subjectto variation as..desired-,..but.- that care should .be takeniinproducing the reaca tiou ,by heat between .the clay and Sodium silicate,thatan aetualiusion 0t themixtureiorminn the. coating is. not produced.as; the EYOidEIl-Cfle of.- fusion providesan advantageous coating andones which ,can .be economically and conveniently: pro-. duced .and ;at.the same time prevents org-retards release of impurities; from .the.base granules (in-v the. event v that, they contain impurities) and;thereby obviates varying. or; deteriorating the resultant effect onithecolor: tone. of th oa in s produced.

The. gram-Wes mentioned inthe above. i'ormu aemay be considered b03 18of such; size that. they willpmylgiwnbut retained o screen. Howev r; orlarger granules,,may beemplqyed,- but, for; similar. results, theamounts oi, coating ins-m i: ents. should. be varied in accordancewithvariationsin the surface area of. each-ton orr nit; weight ofgranules.

As distinguished from prior arttknowutomeh my invention produces. anZinsoluble-and weather-rresisting coating which isof. antinsolubleandaweather-resisting, character. throughout. its. n: tire depth, whereas inthe prior artknowniomee there is produced. merely a skinefiect, andsthacoatings oi'. the prior. art are not possessedfiithe; character ofinsolubility. throu hout their. entire;

depth;

' mmy process it anpearsthat. dehydration. of the mixtures containinsodium; silicate or. the like takes placeshort of. actualfusion of.said: mixtures (in fact; sodium. silicate, willbedehyrdratedattemperatures far below the fusionpoint, thereof) andat thesametime the.sodiumsilicate reacts with theclay (and alsowiththe feldsparand/orcryolite ifithe latter. is present). by com.-

binati-on, to form an insoluble sodiumalminum. silicate which is a.distinctly chemical.reactionl as produced according to myinventionandnot, to be found in-the rior art known to me..

' The product of a metallic oxide-containing component and an,alkali-bearing component for example, kaolinand alkali'silicate, e. gsodium, silicate (with or without feldspar; sodium.

aluminate, etc as disclosed by me, may be of v variable composition, theinsolubility or, resista ance of 'such product-or coatingto-weatherbeing a function of this composition;

In some instances where this invention is emwe. cemvesmeus,

COATlNG B PLAS'H Cross Reference ployed as a coating for granulatedslatefitmay be desirable to make certain changes in the proportions,inasmuch as slate itself contains some clay, but the amount of claycontained in slate is not sufficient to react with the sodiumsilisilicate. By this reaction the entire coating of each granulethroughout the depth of the coating is rendered waterproof, insolubleand weather-resisting.

In the case of the employment of sodium dichromate as thealkali-containing component, it may be-desirable to go to highertemperature limits to produce the required reaction and rengranule Ihave successfully employed the ingredients and their proportions asfollows:

Slate grams 500 Kaolin do 5 Red iron oxide do 4 dium silicate solutionsp. g. 1.3 cc

The above formula is similar to Formula 1 above except for the basegranule here specifically illustrated.

It will be understood that in the case of slate the formula lastmentioned above may be varied as desired, depending upon the porosity ofthe slate.

Other materials, e. g. cement compositions, are suitable for my purposesand may serve as base granules provided such compositions are of acharacter which will withstand the temperatures necessary for roastingor firing, e. g. temperatures of 850 or 900 to 1450 F., the toptemperature employed ordinarily being at least l000 or 1050 F. wherecryolite or other like alkali fluoride, or equivalent, is present withthe kaolin-sodium silicate mix and usually being l350, or 1400 or even1450 For so in the absence of an alkali fluoride or equivalent in theclay-alkali silicate mix, such top temperature however preferably beingbelow the fusion point of the kaolin-sodium silicate mix and preferablyalso below the fusion point of the sodium silicate itself. I have foundthat alkaline earth carbonates do not, by themselves, render sodiumsilicate sufficiently insoluble to be used as a coat-= ing on granulesor the like. In producing coated granules, as herein illustrated, wherequartzite or various other materials may serve as the base granule, Ihave found kaolin or similar clay to be a particularly advantageousingredient of my coating composition in order to arrive at a permanentand insoluble color-bearing coating,

der the same insoluble, andfin this connection, temperatures high enoughto effect at least partial fusion, and also temperatures sufficient toeffect substantially complete fusion, are contemplated. However, it willbe understood that the preferred practice of this invention involvesreacting an alkali silicate (which is usually sodium silicate) 'with amaterial preferably of the nature of kaolin (or other clay, e. g. of thepyrophyllite or kyanite type) 'at temperatures within the range of 900or 1050 to 1450 F. I v

While the present invention'has herein been specifically illustrated andexamples of specific proportions of ingredients, temperature conditions,etc., have been given, it will be understood that such illustrations andexamples are only exemplary and not limitative, and that allmodifications and variations within the scope of this appliactibn and/orwithin the scope of the appended claims are comprehended.

WhatIclaimis: I 1. As a new article of'manufacture, roofing granules ofthe class described having on the exterior thereof a substantiallynon-blooming insoluble coating, said coating consisting substantially ofthe heat reaction product of hydrous plastic clay and sodium silicate,said product of reaction being produced at temperatures belo the meltingpoint of the clay and sodium silic mix and above the dehydration pointoi. said sodium silicate, said coating being substantially free ofwater-soluble salts of sodium.

, 2. As a new article of manufacture, roofing ture above the dehydrationpoint of sa d alk li which latter comprises a neutral matrix hayingdisseminated therein a coloring material or pigment of the colordesired. From the foregoing it will be observed that my coated granulesmay be produced by the steps of:

(1) Wetting the quartz granules with an aqueous solution of analkali-bearing material such as sodium silicate, or perhaps, with asolution of sodiumaluminate or sodium dichromate;

(2) Adding a metallic oxide-bearing component, such as clay or itsequivalent and a pigment in desired proportions thereto; and

3) Then applying heat at least above the dehydration temperature of thecoating mixture, usually above 850 F., and normally above 950 or 1000 F.with a top temperature in excess of 1250 F, being common, but regulatingthe degree of heat below the fusing point of the coating mixture,preferably below about 1450 F., so as to produce a reaction between thesodium silicate and clay to produce an insoluble, weather-resistantreaction product thereof which may be silicate but below the fusionpoint both of't c said alkali silicate and of the clay and sodiumsilicate reaction product and said reaction product being substantiallyfree of water-soluble alkali salts. I

3. As a. new article of manufacture, roofing granules of the classdescribed having on the .51:- terior thereof a substantiallynon-blooming coating, said coating consisting substantially of thereaction product of hydrous plastic clay and 'sodium silicate and beingsubstantially free from water-soluble salts of sodium.

4. As a new article of manufacture, roofing granules of the classdescribed having on the exterior thereof a substantially non-bloominginsoluble colored coating, said coating consisting substantially ofpigment and the reaction product of hydrous plastic clay and sodiumsilicate, and being substantially free from water-soluble salts ofsodium.

5. A new article of manufacture, granulated material having a weatherresisting color bearing coating on the individual granules thereof, theprimary component of which comprises the reaction product of heatcementation" of a soluble alkali bearing silicate and a clay containinga pigment.

6. A colored coatedgranulated material including a mineral base granule,havingaweather resisting coating thereon consisting, ofheatcementitious" reaction product of sodium silicate and claycontaining apigment wherein the-productihas been dehydrated to an extent short of'7. A colored coated granulated material comprisinga mineralbasegranule, a weather resisting-colorbearing coating thereon comprisingsodium silicate and kaolin containing a pigment and whereimthe sodiumsilicate and clay are reacted by heat short of actual fusing of the twotl'alut to a temperature-to produce fheat cements- On. a I

8.- Asa new. article of manufacture .a substantially nonereactive.granule having on :the exterior thereof a substantially non-bloominginsoluble coating, said coatingcomprising the heat reaction product ofhydrous plastic clayand sodium silicate,- said reaction product beingproduced within a temperature range above 900 1 2, said coating, beingsubstantially free or watersolublesaltsofsodium.... i p i In asurfacingmaterial, a bituminous coated backing, and a layerof granules thereon.said granules being individually coated on the exterior thereof with asubstantially non-bloomingicoating, said coating comprising the reactionproduct ofhydrou v plasticclay and sodium silicate and beingsubstantially free .zi'rom water-soluble salts ofsodillmw i 10. as a newarticle of manufacture, weatherresisting granules of the-characterdescribed havingon the exterior of refractory, quartz-bearing basegranulesi.a substantially non-blooming insoluble redcolored coatingcomprisinga rediron oxide pigment disseminated in the-heat reactionproductmtkaolid and sodium silicate produced at temperatures within. therangeof 950 and 1450". F. .and, not. higher than substantially themelting point of the said sodium silicate, a maximumreaction-temperature of. at least 1250 F". beingemployed, said coatingbeing substantially 7 free of water-soluble salts or sodium.

, 1l.- As, a new=articlef manufacture; weatherof colored :granulesof'theacharacter defined in claim 10. I .71

13. A building or rooflngsheet material comprising aflbrous backing anda bituminous adhesive material havinga weather-resistant coating ofcolored granules of the character defined .in

claim ll 14. Themethodiof coloring granulesv of, the classdescribed,which consists in applyingcto the same coatings of a hydrousplastic clay and so.- dium silicate, one of said coatingshaving thereina coloring pigment and finally heatingsaidgranules to atemperaturesuflicientlythigh to react said coatings in situ inter seand produce onsaid particles an insoluble colored coating.

Y 15. The method of coating granules of the class producing acementitious reaction product a priresisting-granules of thecharacterdescribed having on the-exterior thereof a substantially nonbloominginsoluble blue colored coating=compris- 7 ing: ultramarine blue :pigmentdisseminated in the product 0! reaction of kaolin and sodium silicateproduced at temperatures within the range marilyfrom .an alkali silicateand a clay containing a pigment n the surface of a base granule by theapplication-otheat short-of actual fusing ofrthe -product. -.v v1'1. Themethod or producingcoatings on granulated material which includesreacting an alkali silicate and a clay by heat .on. the surface'of aheat-resistant base granule .to produce an insoluble weather resistingcoating thereon and con trolling theheat treatment withinlimits abovesubstantially that toattain a dehydration of the;

coating but short of fusion .thereof.-.

18 The method of producingcoatings on '7 ulated material which includes.reacti-ngen alkali silicate and a clayaby heat in excess -01? 850 onthe suriace of a heat resistant. base granule heat cementitious'!coating thereon; 1,

19. The method of producing colored .co tings on granulatedmaterialwhich includes the employment of a base granule having heat resistant toproduce-in situ an, insolublaweatherresisting qualities, moistening thesurface of the granule 'i .with a sodium silicate solution then.subjecting the thus coated granule to agitation in the presence of amixture of a clay and pigment, and

of 1000 to.1250. FL", said coating-being substantiall'y tree-o1-water-soluble salts. of sodium; 12; A building material or roofing sheet"com prising a fibrous backing and 'a bituminous adhesive materialhaving a weather-resistant coating .then heating to causeheat.cementation.": f

20. In a roofing sheet, avsuriace coated with granulated materialhavingacoating asset forth intheulastrpreceding claim.. I I

